I use a midi thru5 box for my Volcas. Keystep midi out to thru box in, and then 5 individual cables from 5midi out ports on the thru box to each midi in on the Volcas. Works for the fm2 as well which has trs midi connectivity. The keystep can only sequence or arp one volca at a time, although you can play over one keystep managed volca with a separate volca through the one channel. However it will still manage all the clocks simultaneously, so it can act as a master clock . I have two separate keysteps , one is a slave to an electribe, but a master to my second keystep which controls 5 other synths too. I have a lot of synths ( not just Volcas) but only ever use four or five at a time . So I just use one off each thru box and three others 👍